Radiation Detector Products

Centronic produces detectors for monitoring of alpha, beta, gamma, X-ray and neutron radiation. These detectors are designed to suit a wide range of demanding applications.

Centronic offers semiconductor based devices for the detection of various forms of radiation. Common examples of use are baggage scanning for security applications, e.g. airports, and medical imaging.

Centronic X-ray proportional counters provide high resolution performance at low X-ray energies. This feature makes these counters ideal for X-ray fluorescence spectroscopy, thin film thickness gauging and Mossbauer studies.

Centronic helium-3 (3He) neutron counters are sensitive to thermal neutrons and can be used in conjunction with a moderating material for detection of higher energy neutrons. 3He counters are commonly used in Nuclear Material Assaying (NMA), decommissioning, waste management and fuel fabrication systems. In conjunction with fast neutron sources, 3He counters can be used to monitor moisture content in soil and concrete or to monitor soil content within strata during exploration drilling. A growing application for 3He counters lies in security applications such as vehicle monitoring.

Centronic boron trifluoride (BF3) proportional counters are sensitive to thermal neutrons but are less sensitive to gamma radiation than 3He Counters (Centronic BF3 counters can be used in gamma fields up to 1 Sv /hr). Examples of common use are thermal neutron diffraction, neutron spectroscopy, mixed waste monitoring, soil moisture detection and monitoring of nuclear reactors operating at low power.

Centronic boron lined proportional counters have a similar construction to BF3 and 3He proportional counters. However, the neutron detection is by means of a boron coating rather than boron or 3He in a gaseous form, resulting in a higher neutron sensitivity. Typically, boron lined proportional counters are used where the temperature limitations of BF3 counters prevents their use.

Centronic REM (Roentgen Equivalent Man) counters are used in conjunction with appropriate electronics to measure total human body neutron dose. They are designed to be portable and to give a high neutron sensitivity over a wide range of neutron energies (0.025 eV to 10 MeV). Spherical REM counters, (which incorporate a spherical 3He counter) are designed to provide omnidirectional monitoring.

Centronic spherical 3He counters can be used in conjunction with spherical moderating materials of various sizes to allow measurement of neutron fluxes at various energies. The PTB Bonner sphere and "NEMUS" systems are available through Centronic.

Centronic ionisation chambers have excellent long-term stability of calibration and long operating lifetimes, making them ideal dose rate monitors for use in environmental and area monitoring. Some types of ion chamber include a re-entrant tube, allowing insertion of small radioactive sources, or a central hole, to allow sources to be passed through the ion chamber. This type of ion chamber is suited to isotope monitoring and dose calibration.

Centronic boron ion chambers can be tailored to measure neutron fluxes over the range required for the application. Uncompensated boron ion chambers are generally used in regions of high neutron flux where the gamma flux, which will also contribute to the output measurement, is not significant in relation to the neutron flux. The most common application of boron ion chambers is therefore in reactor control detectors for operation at full reactor power.

Gamma compensated boron ion chambers are also available for use in reactor control instrumentation. These are more suited to high mixed fluxes found near a reactor, being capable of compensating for gamma fluxes in these environments. Compensation for the gamma flux allows this type of device to operate at lower neutron flux levels.

Centronic fission chambers can be used in either pulse or direct current (dc) mode. When used in pulse mode, non-neutron pulses can be discriminated against fairly easily, even at low neutron fluxes. This makes pulse fission chambers ideal for use in high mixed fields. This makes them suitable for use as part of in-core or ex-core nuclear instrumentation. Small fission chambers, such as the Centronic FC4A, are designed for use in pulse mode for flux scanning in narrow tubes in the region of fuel elements. Fission ion chambers are generally only used in dc mode for reactor control instrumentation. However, fission product activity limits the dynamic range of dc fission ion chambers to, typically, the top 2 decades of reactor power. A wider range of neutron flux measurement can be obtained using fission chambers by use of the Campbelling measurement technique

Some Centronic detector products are required to operate in an environment isolated from their control instrumentation. Centronic have experience of manufacture of electrical feedthroughs to enable operating voltages to be applied to the detector, and signals to be passed from the detector to the instrumentation, through the isolation boundary.

Centronic detectors often form part of a greater mechanical assembly, which may incorporate moderating and/or other specialist materials. Centronic supplies such ancillary equipment with its detector products when required.